1. Field of the Invention
The invention relates to network communications, and more particularly to Ethernet communication circuits.
2. Description of the Related Art
An Ethernet network system comprises at least one port for communication with link partners via Ethernet standard protocols. When the Ethernet network system comprises more than one port, the Ethernet network system is referred to as a multi-port Ethernet network system. Referring to FIG. 1, a block diagram of a conventional multi-port Ethernet network system 100 is shown. The network system 100 comprises a plurality of ports 111˜11N, a plurality of Ethernet circuits 121˜12N, and a central processing unit (CPU) 150. Each of the Ethernet circuits 121˜12N comprises an Ethernet physical layer transceiver and a media access controller. A plurality of link partners are coupled to the Ethernet network system 100 via the ports 111˜11N. Each of the ports 111˜11N is coupled to one of the Ethernet circuits 121˜12N, and the Ethernet circuits 121˜12N are couple to the central processing unit 150.
When a link partner sends Ethernet packets to a target port selected from the ports 111˜11N, the target port delivers the Ethernet packets to a corresponding Ethernet circuit. The Ethernet circuit then retrieves data from the Ethernet packets and sends the retrieved data to the central processing unit 150. When the central processing unit 150 wants to send data to a link partner, the central processing unit 150 sends the data to a corresponding Ethernet circuit, and the Ethernet circuit generates Ethernet packets according to the data and delivers the Ethernet packets to the corresponding port. The port then sends the Ethernet packets to the link partner.
Because each of the ports 111˜11N correspond to one of the Ethernet circuits 121˜12N, the Ethernet network system 100 comprises the same number of Ethernet circuits 121˜12N as that of the ports 111˜11N. The Ethernet circuit 121˜12N, however, costs a lot, and the large number of the Ethernet circuits 121˜12N further increases the total manufacturing cost of the Ethernet network system 100. To reduce the manufacturing cost of the conventional Ethernet network system 100, a new-type of multi-port Ethernet network system with a low cost is therefore required without degrading the performance of the ports of the Ethernet network system.